I mean, there's nothing wrong with speculating, that's what fanboys love doing best... It's just when it goes that step further... Then people start joining the forum and because people are talking about speculation like it's fact, they TAKE it as fact and then before you know it, it's completely out of control.

That's exactly what happened with The Avengers thread and it made that place largely unbearable for a long time.

This is the best when it happens with fancasting.

"Nathan Fillion should totally play X!"
2 Months Later
"What?! This is bull ****! I thought Nathan Fillion was playing X!"